That Time I Hid the Script

I, Chen Xiaobai, trained painstakingly until I became an immortal. I worked diligently my whole life, only for the protagonist to land a single strike that let him surpass my level and wipe out everything I'd achieved?

Didn't see that coming, did you? Your Grandpa Chen has been reborn in another world, and this time I've brought not only my memories but my magic too. As soon as I get back, I'll crush you, you cheat with your protagonist aura.